This invention relates generally to the field of folding machines for folding sheets of paper of different lengths into various fold configurations, and more particularly to a folding machine having the capability of either folding sheets of paper which exceed a predetermined minimum length or merely passing sheets through the machine without folding which are shorter than the predetermined minimum length.
The sheet folding machine of the present invention was designed and developed for use as a folding machine module to be incorporated into a sheet processing apparatus which performs several operations on sheets passing through the apparatus. Several forms of such apparatus as heretofore known are utilized to assemble together various forms of documents and to prepare them for mailing, typically operating on multiple sources of documents to feed, sever, fold, collate, insert and stack all in one continuous operation and at relatively high speed. A typical apparatus of this nature is used to assemble and prepare for mailing such items as telephone bills, credit card charge account bills, monthly bank statements, sweepstakes entries, and any of a variety of other examples where the finished mail piece includes a plurality of different sized items, only some of which are folded.
A typical apparatus of this nature would include several sheet processing modules or components each of which performs a particular function on sheets passing through the apparatus. For example, an apparatus for processing credit card charge account bills would include a pair of feeding devices for simultaneously feeding a pair of webs, each web having discrete forms or documents thereon separated by score lines, with the documents on one web being of a different length than the documents on the other. The webs are fed into a bursting module where they are separated from each other by bursting rollers, from where they are fed into an accumulator module where they are stacked in individual piles until the desired number of forms or documents from each web has been accumulated, all under the control of appropriate software. In some installations, only one web is involved, since the short documents are already in sheet form and are fed into the system from a sheet feeder, as more fully explained below. Thereafter, the sheets from each stack are fed through a folding module which folds the sheets from each stack into one of several different fold configurations as desired to fit into appropriate envelopes for mailing. After passing through the folding machine, the folded sheets from each stack are collated into a single pile, which is then either fed into an inserting module for inserting the folded collation directly into a mailing envelope, or it is passed into a collating module where additional material is added to the folded collation, after which it is fed to the inserting machine for insertion into an envelope. In a typical installation, the filled envelopes are then stacked and either manually or automatically fed to a mailing machine which closes and seals the flaps of the envelopes and prints an appropriate postage indicia on the face of each envelope.
The commercial advantage of such multi-function sheet processing apparatus, especially when operating at a high rate of speed, will immediately be apparent when one considers the tens of thousands, perhaps hundreds of thousands, of mail pieces as described above which are prepared and sent to customers each month by a single mailer. Obviously sheet processing apparatus of this nature is very complex to manufacture and therefore very costly, and has utility only in installations in which a very large number of individual mail pieces are assembled and prepared for mailing on a frequently repetitive basis. It is therefore of the utmost importance to enable the processing apparatus to operate at the highest possible speed and degree of reliability in terms of down time, either from maintenance or breakdown.
One aspect of certain sheet processing installations that has been the cause of a significant problem is that of handling sheets which are too short to be folded, or at least are of a sufficient short length that it is desired not to fold them prior to their being inserted into an envelope. As described above, a sheet folding module is one of the components of the sheet processing apparatus that is integrated into the system for handling all sheets being fed seriatim through the apparatus. Many modern day forms of multiple sheet mail pieces include forms or documents which are initially scored on the web sufficiently short that they will fit into a suitable mailing envelope without being folded. Also, in the case of bank statements, the cancelled checks of the bank customer that are normally included with the pages of the customer's statement are already short enough to fit into a mailing envelope and therefore are not folded. Thus, the problem that is presented is how to feed such short documents through the folding machine module without folding them and at the same time preventing them from jamming up in the folding machine because of their short length.
In conventional folding machines, which include one or more buckle chutes into which sheets are fed by a plurality of feeding and folding rollers, a sheet of given length is fed into the chute until the lead edge of the sheet abuts a fixed back stop which arrests further movement of the sheet while a substantial portion remains outside of the buckle chute. Continued rotation of the feed rollers forms a buckle in the sheet which is directed into the nip of a pair of rollers which forms a fold in the sheet. If additional folds are required, the partly folded sheet is fed into another buckle chute until the new lead edge abuts a fixed back stop which again arrests movement of the partly folded sheet while a substantial portion still remains outside of the buckle chute. A second buckle is now formed which is fed into the nip of another pair of rollers to form the second fold in the sheet, after which the sheet may be ejected from the folding machine. Folding machines of this type have long been well known and complete descriptions thereof are replete in the art.
During the preceding operation, the sheet is under the control of at least one pair of feeding and folding rollers at all times while it is in the folding machine. It should be apparent that if a sheet is fed into the folding machine that is too short to remain under the control of at least one pair of rollers while part of the sheet is in a buckle chute, the sheet will not exit from the buckle chute as it should under normal operating conditions, but rather will remain in the buckle chute and cause a serious paper jam in the buckle chute when further sheets are fed thereinto.
In some continuous sheet processing installations, this problem has been solved by providing an alternate feed path for sheets which are too short to be fed into the folding machine module and folded, the alternate feed path bypassing the folding machine module so as to deposit the short documents in collated fashion just downstream from the folding module. This solution requires a separate feeding module which is positioned outside of the normal feed path through the processing apparatus and is located therealong to continuously feed short documents into the feed path of the processing apparatus downstream from the folding module so that the short documents are collated with the folded documents in another accumulating module. This arrangement suffers the disadvantages of requiring additional hardware of substantial complexity, additional software and controls to coordinate the operation of the external feeding apparatus with the sheet processing apparatus, providing further opportunity for breakdowns, added cost, and diminished speed and efficiency due to the added step of having to separately collate short documents with longer folded documents in a separate step.